Directional antenna system



ly 1940- K. KOSCHMIEDER DIRECTIONAL ANTENNA SYSTEM Filed July 17, 1937Patented July 9, 1940 UNITED STATES PATENT FHQE DIRECTIONAL ANTENNASYSTEM Application July 17, 1937, Serial No. 154,153 In Germany July 18,1936 1 Claim.

Directional antennae are known which are composed of individual antennaeby which mainly the vertically polarized waves are received. In order tosuppress the horizontal component,

special precautions are necessary which reside in part in theconstructional arrangement of the individual antennae themselves and inpart in the provision of proper screenings. The antenna system bestknown in this regard is the so-called Adcock antenna which consists offour vertical radiators erected in the angles of a square andinterconnected crosswise. Such systems if carefully built up arefaultless in operation. However it has been experienced that in certaincases 16 the desired result is not obtained. Investigations have shownthis to occur if the electric earth is not homogeneous or not horizontalor fails to fulfill both these requirements.

A vertical antenna has a vertical characteristic m above the earthssurface if the electric constants of the ground are the same in alldirections. Every discrepancy in this regard entails that a verticalantenna does not only transmit or receive vertically polarized waves butalso transmits horizontally polarized waves or is excited by such waves.A vertical antenna erected on not homogeneous ground is in electricalrelation of the same properties as if it were standing aslant.

In order to compensate for the error arising in this way the inventionproposes so to incline the individual antennae in relation to theelectric earth that horizontally polarized waves shall not be radiatedor received, as the case may be. For

5 effecting the invention, preferably self-supporting antennae areemployed which are so mounted at their lower ends that they can bepositioned aslant. This arrangement has still other advantages over thecustomary antennae, as will be 0 understood from the followingdescription, reference being had to the accompanying drawing in whichFig. 1 is a partially diagrammatic sectional elevation representing oneembodiment of the 45 invention, Fig. 2 is a diagrammatic plan view of anantenna system composed of antennae of the construction shown in Fig. 1.

The antenna I is a self-supporting mast which at its lower end ismounted on an insulated platform 3 of a tripod 2. The antenna is held inposi tion by clamps formed of insulators 4, 4 and 5, 5. Insulator 8serves to sustain the weight of the antenna i. The insulators l, 5 arearranged to hold the antenna against lateral displacement and areradially displaceable by means of screws 5, for instance, guided insuitable bushings of the tripod 2, as shown in Fig. 1. Instead of this 5arrangement for displacing the insulators 5, 4 anyyther device may beemployed. It will be seen that by displacing the insulators i, 5 antennai can be given positions difierent from the normal one, as shown indotted lines.

The system represented in Fig, 2 is an Adcock antenna. In each of thefour angles of a square an antenna l is erected which is of theconstruction illustrated in Fig. 1. In the middle of the system atransmitting or receiving apparatus 5 A is located. The means by whichthis apparatus and the antennae l are interconnected is in a purelydiagrammatic manner represented by lines 8. In this system theindividual antennae I are each given an oblique position which is suchthat 20 the horizontal polarization shall be suppressed in alldirections.

The vertical antennae of the customary Adcook arrangements are a Wirefixed at its upper end to a cantilever carried on a wooden pole. This 25arrangement too allows of efiecting the invention, the pole and thus thecantilever having to be given an oblique position to such end. Thisarrangement however has the disadvantage that with rainy weather the wetpole will have an influence upon the radiation characteristic. The novelarrangement has the advantage that field distortions are avoided.

In addition, systems as provided by the invention are advantageousinasmuch as they are easy to transport and to build up.

What is claimed is:

In a directional antenna system for receiving vertically polarizedenergy only, comprising an upright antenna mounted above the ground,said ground having non-homogeneous conditions affecting the polarizationof resultant received energy, the method of compensating for saidnonhomogeneous conditions to effect a substantial neutralization of theeffects on the polarization, comprising adjusting said antenna about apoint at its lower end to a position inclined with respect to the groundat such an angle that the antenna will receive only vertically polarizedwaves, and maintaining said antenna in said adjusted position.

KURT KOSCHMIEDER.

